Distillation and conversion of hydrocarbon oils



29, 1940- K'. SWARTWOOD ET AL 36 DISTILLATION AND CONVERSION OF HYDROCARBON OILS Original Filed July 26, 1953 (Tana e ATTORNEY.

Patented Oct. 29, 1940 "stars-s! "UNlTE :3:

TENT OFFlCE DISTILLAT'ION AND CONVERSION 'OF HYDROCARBON OILS Ware Application July 26, 1933, Serial No. 682,212 Renewed September. 12, 1938 r 6 Claims.

This invention particularly refers to an improved process and apparatus for the distillation and separation of hydrocarbon oil into low boiling and high boiling fractions followed by the pyrolytic conversion of either of said fractions or the simultaneous conversion of both under independently controlled heating conditions in the same cracking system. v I

v The novelty of the present invention resides primarily in the improved method and means of effecting distillation of the charging stock whereby its separation into low boiling and high boiling fractions is accomplished and this feature of the invention comprises heating the charging stock to the required temperature to effect its fractional distillation by directly commingling therewith a regulated portion of the highly heated products from either or both of the cracking coils of the system.

One specific embodiment of the presen'tinven- 'tion comprises subjecting hydrocarbon oil charging stock for the process to distillation and fractionation whereby it is separated into low boiling and high boiling fractions, subjecting the high boiling fractions to conversion temperature at superatmospheric pressure in a heating coil and communicating reaction chamber, separating the resulting vaporous and residual conver- 'sion products, subjecting the vapors to fractionation whereby their insufficiently converted components are condensed as reflux condensate, returning the reflux condensate to the heating coil for further conversion, subjecting fractionated vapors of the desired end boiling point to condensation, collecting and separating the resulting distillate and gas and introducing a regulated portion of the highly heated oil fromthe heating coil into direct con-tact with the char ing stock undergoing distillation for the purpose of supplying the required heat thereto to effect said distillation andfractionation.

It is also within the scope of the invention to subject all or a selected portion of the low boiling fractions of the charging stock to conversion in the same cracking systennin which case such conversion is preferably accomplished under independently controlled more severe conditions than those employed for the .conversion of the high boiling fractionsby passing the low boiling oil through a separate heating coil wherein it is subjected to the desired independently controlled conversion conditions of elevated temperature and super-atmospheric pressure and the resulting highly heated products are discharged into the reaction chamber to commingle and be subjected to continued conversion therein with the products from the first mentioned heating coil. In zt'hiscase a regulated portion of [the highly heated oil from said separate heating coil may be utilized, either alone or in conjunction with a regu- '5 'lated portion of the oil from-the first mentioned heating coil, as the heatcarrying medium to effect distillation of the charging stock by direct contact therewith.

Various modifications of the specific operation 10 above described may be employed without departing'from the scope of the invention. A few such modifications will-be more apparent with. referenceto the accompanying diagrammatic drawing and the following description thereof. 15 The drawing illustrates one specific form of apparatus in which the process of the invention maybe accomplished. It will be understood, however, that the invention is not limited to the vspecificform of apparatus illustrated nor to any :20

other specific form of apparatus, since the features of the invention may be employed to advantage in a wide variety of distilling and crack-.- ing systems.

Referring to the drawing, raw oil charging ,25 stock for theprocess, which may comprise,' for example, crude petroleum or any other hydrocarbon oil of relatively wide boiling range which may or may not contain a substantial portion of motor fuel'frac tions, is supplied through line i ;3 and valve 2 to distilling and fraotionating col umn 3, wherein it is subjected to distillation and fractionation to effect its separation into relatively low boiling and relatively high boiling fractions. The charging stock may, of covrse,,; be preheated in any well known manner (not shown) prior to its introduction into column 3, for example, by indirect contact and heat exchange with relatively'hot vaporous or liquid products of the process or by means of heat from an external source. However, in accordance with the features of the invention, a substantial portion or all of the heat required for distillation of the charging stock is supplied thereto by specific means which will be later more fully described. -5

. Low boiling fractions of the charging stool: of the desired end boiling point are removed from the upper portionv of column .3 through line 4 and valve 5 to condenser 6, wherein they are subjected to condensation and cooling. The result- ,59 ing distillate andvgas passes through line 1 and valve 3, to collection and separation in receiver 9. Gas may be released from the receiver throughline Ill and valve H and a portion or all of the distillateniay, when desired, be with- ,55

drawn through line l2 and valve E3 to storage or to any desired further treatment. A regulated portion of the distillate collected in receiver 9 may, when desired, be recirculated, for example, by means of line l4, valve l5, pump I6, line H, line l8 and valve IE] to the upper portion of column 3 for the purpose of assisting cooling and fractionation in this zone, serving as a means of wherein heating coil 2| is not employed is en- I tirely within the scope of the invention.

When the charging stock contains a substantial portion of materials within the boiling range of gasoline it is also within the scope of the invention to remove this material or only low boiling components thereof of satisfactory anti-knock value, in case its higher boiling components are of inferior motor fuel characteristics, removing the former from the system as the overhead distillate product from column 3 and removing the latter either alone or together with higher boiling oils such as naphtha, kerosene or kerosene distillate, light gas oil or fractions of such materials as one or a plurality of side cuts from the fractionator by well known means (not shown), and supplying the same to heating coil 2| for conversion, by well known means (not shown). In case the charging stock contains gasoline or gasoline fractions substantially all of which are of unsatisfactory motor fuel characteristics, particularly with respect to their anti-knock value, they may be collected in receiver 9, as previously described, either alone or together with higher boiling fractions of the charging stock, such as previously mentioned, and supplied, in the manner already described, to heating coil 2| for conversion. In either case the conversion conditions employed in the heating coil are of a character which will effect a substantial improvement in the anti-knock value of the motor fuel or motor fuel fractions without excessively altering their boiling range and any higher boiling oils supplied to heating coil 2| are limited to those of the character which may be converted to produce substantial yields of good quality motor fuel under the conditions. employed for the reforming of the gasoline in this zone. The invention is, of course, not limited to the treatment of charging stocks containing motor fuel or motor fuel fractions and any desired separation between low boiling and high boiling components of the charging stock may be made in column 3, the end boiling point of the light fractions removed as the overhead product from column 3 and withdrawn from the system or supplied to heating coil 2| for conversion ranging, for example, from 400 to 650 F., or thereabouts. When a separate side stream is withdrawn from column 3, as previously described but not illustrated, to be supplied to heating coil 2| for conversion, its initial boiling point may range, for example, from 200 to 450 F. With an end boiling point of from 400 to 650 F., or thereabouts. It is, of course, within the scope of the present invention, when the overhead distillate product from column 3 is supplied to heating coil 2|, to supply all or a regulated portion of the entire overhead product from column 3, including any gas, to heating coil 2|, by means of a suitable vapor pump or compressor (not shown) without the loss of heat involved by condensation of the distillate in condenser 6.

The high boiling fractions of the charging stock which remain unvaporized and/or are condensed by fractionation in column 3 are removed from the lower portion of column 3 through line 22 and valve 23 to pump 24 by means of which they are fed through line 25 and may be directed through line 26, valve 2'! and line 28 to conversion in heating coil 30 or the oil from heating coil 2| may be introduced into the cracking system at one or a plurality of other suitable points therein, as will be later more fully described.

Heating coil 30 is located within a furnace 3| of any suitable form by means of which the required heat is supplied to the oil passing through this zone to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure and the heated oil is discharged through line 32 and valve 33 into reaction chamber 34.

Chamber 34 is also preferably maintained at a substantial superatmospheric pressure and, although not illustrated in the drawing, is preferably well insulated in order to conserve heat so that conversion of the heated oils supplied to this zone, and more particularly their vaporous components, may continue therein. In the case here illustrated, both vaporous and liquid conversion products are withdrawn in commingled state from the lower portion of chamber 34 through line 35 and valve 36 and are introduced into vaporizing chamber 31.

Chamber 3! is preferably operated at a substantially reduced pressure relative to that employed in the reaction chamber by means of which further vaporization of the liquid products supplied to this zone is accomplished. Vaporous and liquid products of the process are allowed to separate in chamber 31 and the unvaporized residual liquid is withdrawn through line 38 and valve 39 to cooling and storage or elsewhere, as desired. The vapors pass from chamber 31 through line '40 and valve 4| to fractionation in fractionator 42.

Components of the vapors boiling above the desired final light distillate product of the process are condensed as reflux condensate in fractionator 42 to be withdrawn therefrom through line 43 and valve 44 to pump 45 by means of which this material is returned through line 28 and valve 29 to further conversion in heating coil 30.

Fractionated vapors of the desired end boiling point are withdrawn, together with uncondensable gas, from the upper portion of fractionator 42 through line 46 and valve 41 to be subjected to condensation in condenser 48. The resulting distillate and gas passes through line 49 and valve 50 to collection and separation in receiver 5|. Uncondensable gas may be released from the receiver through line 52 and valve 53 while the distillate may be withdrawn from this zone through line 54 and valve 55, to storage or to any desired further treatment. A regulated portion of the distillate collected in receiver 5| may, when desired, be recirculated by well known means (not shown), to the upper portion of fractionator 42 for the purpose of assisting cooling and fractionation in this zone in order to maintain the desired vapor outlet temperature from the fractionator and thus control the end boiling point of the final light distillate product of the process.

The oil supplied, as previously described, to heating coil 2|, when this zone of the system is employed, is subjected therein to the desired conversion temperature, preferably at a substantial superatmospheric pressure, by means of heatsupplied from a furnace 56 of any suitable form. The heated oil is discharged from heating coil 2| through line 5'! and, in the case illustrated, may pass all or in part through line 58 and valve 59 into'reaction chamber 34, commingling therein with 'the heated oil from heating coil and being subjected therewith to continued conversion in the reaction chamber.

In accordance with the provisions of the present invention a substantial portion or all of the heat required for distillation of the charging stock supplied to column 3 is derived by cornmingling a regulated portion of the heated oil from heating coil 2! and/or heating coil'30 with the charging stock. This may be accomplished by directing a regulated portion of the highly heated oil from the outlet of heating coil 2!- through valve 60, in line 51, into the lower portion of column 3 and/or by directing a regulated portion of the heated oil from the outlet of heating coil 30 through line 65, valve 62 and line 51 into the lower portion of column 3. As analternative to this method of operation, a regulated portion of the heated oil passing through heating coil 2| and/or heating coil 30 may be withdrawn from a suitable intermediate point in the coils, for example, through the respective lines 63 and E4, controlled, respectively, by valves. 65 and 66, and directed by means already described, into the lower portion of column 3. The latter method of operation provides a means of avoiding mixing materials which have undergone extensive conversion with the charging stock in column 3, thereby avoiding contamination of the high boiling fractions of the charging stock with heavy conversion products of a residual nature as well as avoiding mixing of unconverted light charging stock fractions with light conversion products. This may be insured by withdrawing the oil supplied as the heat carrying medium to column 3 from the heating coil or heating coils at a point therein where the oil has not reached the ,final conversion temperature or has not been maintained under conversion conditions for a sufiicient length of time to permit the extensive conversion thereof. The latter method of operation will, of course, ordinarily necessitate-the use of a somewhat larger volume of oil as the heat carrying medium, as compared with the first described method wherein highly heated products from the discharge of the heating coil are supplied to column 3. I

As a modification to the operation .above described, which is also within the scope of the present invention, the high boiling fractionsof the charging stock instead of being supplied direct to heating coil 30 may, when desired, be introduced into chamber 3'! or into chamber 34 at any desired point. As illustrated in the drawing, an extension of line .25 containing valve 63 permits the introduction of the high boiling fractions of the charging stock into chamber 31 and a line 6?," controlled by valve "68 permits the high boiling fractions of the charging stock to 'be diverted from line 25 into line '58 and thence to reaction chamberfl l.

.By supplying the high boiling fractions of the charging stock to chamber 31 they may be :subjected lt0'=fll1.th1 vaporization in this zone, the

' vaporous products passing to fractionator 42 to be condensed therein and commingle with the reflux condensate and finally supplied with the reflux condensate to conversion in heating coil 30, while any heavycomponents of the high boiling fractions of the charging stocko'f a residual nature, unsuitable for conversion in heating coil 35 with the reflux condensate, may remain unvaporized in chamber 31, commingling therein with the residual liquid conversion'products of the process. The same is true when the high boiling fractions :of the charging stock are supplied to chamber 34except that, in the'latter case, someconversion of the oil may be accomplished in the reaction chamber, prior to its further vaporization in chamber 31.

When desired, in order to assist vaporization in chamber 31, particularly when high boiling fractions of the charging stock are supplied to this zone and their extensive further vaporization is desired, a "regulated portion or all of the highly heated products from heating coil 2 I may be diverted from line 58 through line 61, valve 68, line '25 and valve into chamber 31; It will be understood that this material may also 'be introduced'in'to the-vaporizing chamber at any other desired point therein by wellknown means (not shown).

' Preferred operating conditions for the process in an apparatus such as illustrated and above described may be as follows: The distilling and frac- 'tionating column-to which the charging stock is supplied is preferably operated at substantially atmospheric or low supera'tmospheric pressure not in excess of 100 pounds, or thereabouts, .per square inch. The tempeprature ofthe heat car rying medium supplied to this zone may range,

for example, from 700 to 1100" F., and'the charg-' ing stock may be heated thereby to a temperature which may range, for example, from 400 to 700 F., or thereabouts. The first mentioned heating coil, to which reflux condensate from the fractionator of the cracking system is supplied, may utilize an outlet conversion temperature within the rangeof 800 to 950' F., or thereabouts, preferably with a substantial supera'tmospheric pressure at this point in the system-of from 100 to 500 pounds, ormore, per square inch. The second mentioned heating coil to which low boiling fractions of the charging stock are supplied, when such a'zone is employed, may employ an outlet conversion temperature ranging, for example, from 900 to 1000" F., preferably with a tially-reduced pressure relative to that employed in the reaction chamber is preferred in the vaporizing chamber and may be either substantially equalized or somewhat reduced in the succeeding fractionalting,=condensing andcollecting por-.

tions of the cracking system.

As a specific example :of one of :the many possible operations of the process of the present invention, the charging stock is an Arkansas crude of about 35 A. P. I. gravity containing less than 5% of material boiling up to 212 F. and containing approximately 30% at 410 F. This material is heated to a temperature of approximate- 1y 650 F. at substantially atmospheric pressure and the evolved vapors are subjected to fractionation whereby the crude is separated into an overhead fraction having an end boiling point of approximately 550 F. and topped crude or bottoms comprising the higher boiling fractions. The topped crude is subjected to a conversion temperature of approximately 900 F. at a superatmospheric pressure of about 275 pounds per square inch. The succeeding reaction chamber is maintained at substantially the same pressure and a substantially reduced pressure of approximately pounds per square inch is maintained in the vaporizing chamber and the succeeding fractionating, condensing and collecting portions of the cracking system. The low boiling fractions of the charging stock are subjected in a separate heating coil to an outlet conversion temperature of approximately 980 F. at a superatmospheric pressure of about 750 pounds per square inch and the heated products are introduced into the reaction chamber. A regulated portion of the oil from the last mentioned heating coil, sufficient to heat the charging stock to the temperature mentioned, is withdrawn from an intermediate point in the heating coil at a temperature of about 850 F. and introduced into the lower portion of the distilling and fractionating column. This operation may yield, per barrel of charging stock, approximately 65% of motor fuel having an octane number of approximately 72 and about 15% of heavy residual oil, the remainder being chargeable principally to uncondensable gas and loss. L

We claim as our invention: 7

1. A process for the treatment of hydrocarbon oil, which comprises subjecting hydrocarbon oil charging stock for the process, of relatively wide boiling range, to distillation for separation into low boiling and high boiling fractions, introducing the latter into a vaporizing chamber of a cracking system wherein its light components are vaporized and separated from its heavier components, subjecting the vapors to fractionation, together with vaporous conversion products of the process, whereby components of the commingled vapors boiling above the range of the desired light distillate product of the process are condensed as reflux condensate, subjecting fractionated vapors of the desired end boiling point to condensation, collecting and separating the resulting distillate and gas, subjecting the reflux condensate to conversion temperature at superatmospheric pressure in a heating coil and communicating reaction chamber, introducing the resulting vaporous and liquid conversion products into said vaporizing chamber at substantially reduced pressure, simultaneously subjecting low boiling fractions of the charging stock to independently controlled more severe conversion conditions in a separate heating coil, commingling the vaporous products from both heating coils, prior to their fractionation, and commingling a regulated portion of the heated oil from said separate heating coil with the charging stock for the purpose of supplying thereto at least a portion of the heat required for said distillation.

2. A process for the treatment of hydrocarbon oil, which comprises subjecting hydrocarbon oil charging stock for the process, of relatively wide boiling range, to distillation for separation into low boiling and high boiling fractions, introducing the latter into a vaporizing chamber of a cracking system wherein its light components are vaporized and'separated from its heavier components, subjecting the vapors to fractionation, to-

gether with vaporous conversion products of the process, whereby components of the commingled vapors boiling above the range of the desired light distillate product of the process are condensed as reflux condensate, subjecting fractionated vapors of the desired end boiling point to condensation, collecting and separating the resulting distillate and gas, subjecting the reflux condensate to conversion temperature at superatmospheric pressure in a heating coil and communicating reaction chamber, introducing the resulting vaporous and liquid conversion products into said vaporizing chamber at substantially reduced pressure, simultaneously subjecting low boiling fractions of the charging stock to independently controlled more severe conversion conditions in a separate heating coil, commingling the vaporous products from both heating coils, prior to their fractionation and commingling a regulated portion of the heated oil from either heating coil with the charging stock for the purpose of supplying thereto at least a portion of the heat required for said distillation.

3. A conversion process which comprises subjecting reflux condensate, formed as hereinafter set forth, to cracking conditions of temperature and pressure in a cracking zone and subsequently separating the same into vapors and residue in a separating zone, simultaneously partially distilling charging oil for the process to form a relatively light overhead fraction, introducing the unvaporized portion of the charging oil to said separating zone and further distilling the same therein, heating said overhead fraction in an independent zone to higher cracking temperature than said reflux condensate and then discharging a portion thereof into the separating zone, contacting another portion of the independently heated overhead fraction with said charging oil to assist the distillation of the latter, fractionating the commingled vapors from the separating zone to condense heavier fractions thereof and supplying such condensed fractions to the cracking zone as said reflux condensate, and finally condensing the fractionated vapors.

4. A hydrocarbon oil conversion process which comprises subjecting the charging oil to distillation in an enlarged externally unheated distilling zone. passing relatively low boiling fractions and higher boiling fractions of the charging oil through separate heating zones and heating the same therein to cracking temperature under pressure, the low boiling fractions being heated to higher temperature than the higher boiling fractions, discharging a portion of the heated higher boiling fractions from the heating zone in which these fractions are heated directly into the distilling zone to supply heat for said distillation, introducing the remaining portion of the heated higher boiling fractions and the heated low boiling fractions into a second enlarged zone and separating the same therein into vapors and residue, and fractionating and condensing the vapors.

5. A hydrocarbon oil conversion process which comprises subjecting the charging oil to distillation in an enlarged externally unheated distilling zone, passing relatively low boiling fractions and higher boiling fractions of the charging oil through separate heating zones and heating the same therein to cracking temperature under pressure, the low boilingfractions being heated to higher temperature than the higher boiling fractions, discharging a portion of the heated low boiling fractions from the heating zone in which these fractions are heated directly into the distilling zone to supply heat for said distillation, introducing the remaining portion of the heated low boiling fractions and the heated higher boiling fractions into a second enlarged zone and separating the same therein into vapors and residue, and fractionating and condensing the vapors.

6. A hydrocarbon oil conversion process which comprises subjecting the charging oil to distillation in an enlarged externally unheated distilling zone to separate lower boiling from higher boiling fractions thereof, passing such separated lower boiling fractions in a restricted stream through a heating zone and heating the same therein to cracking temperature under pressure, removing a portion of the heated lower boiling fractions from an intermediate point in said heating zone and dischargingthe same into the distilling zone to supply heat for said distillation, introducing the remaining portion of the heated lower boiling fractions, after passage through the entire length of the heating zone, into a second enlarged zone and separating vapors from residue therein, and fractionating and condensing the vapors.

KENNETH SWARTWOOD. ALVIN ENGELSTEIN. 

